Briarpatch, don't give up on the thumb muscle. I'm guessing that when the nerve is healed and you start using the hand again, the nerve muscle will slowly come back. I had a ruptured disc in my lower back about 15 or 16 years ago. The sciatica was pretty bad, and it took three spinal injections and several months for it to resolve. In the first couple of weeks, my upper left leg muscle shrunk a good 4 to 5 inches. However, once I was able to walk normal again, the muscle came back to its normal size in a couple of months. Good luck.